Heme induces endothelial tissue factor expression: potential role in hemostatic activation in patients with hemolytic anemia

Authors

  • B. N. Y. SETTY,

    1. Marian Anderson Comprehensive Sickle Cell Anemia Care and Research Center, Department of Pediatrics, Division of Research Hematology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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  • S. G. BETAL,

    1. Marian Anderson Comprehensive Sickle Cell Anemia Care and Research Center, Department of Pediatrics, Division of Research Hematology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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  • J. ZHANG,

    1. Marian Anderson Comprehensive Sickle Cell Anemia Care and Research Center, Department of Pediatrics, Division of Research Hematology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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  • M. J. STUART

    1. Marian Anderson Comprehensive Sickle Cell Anemia Care and Research Center, Department of Pediatrics, Division of Research Hematology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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B. N. Yamaja Setty, Department of Pediatrics, Thomas Jefferson University, Medical College Building, Suite #727, 1025 Walnut Street, Philadelphia, PA 19107, USA.
Tel.: +1 215 955 9821; fax: +1 215 955 8011.
E-mail: yamaja.setty@jefferson.edu

Abstract

Summary. Objectives: We explored the possibility that heme, an inflammatory mediator and a product of intravascular hemolysis in patients with hemolytic anemia including sickle cell disease, could modulate hemostasis by an effect on endothelial tissue factor (TF) expression. Methods: Levels of TF mRNA, protein and procoagulant activity were measured in heme-treated endothelial cells. Results: Heme induces TF expression on the surface of both macrovascular and microvascular endothelial cells in a concentration-dependent manner, with 12-fold to 50-fold induction being noted (enzyme-linked immunosorbent assay) between 1 and 100 μm heme (P < 0.05). Complementary flow cytometry studies showed that the heme-mediated endothelial TF expression was quantitatively similar to that of tumor necrosis factor-alpha (TNF-α). Heme also upregulated the expression of TF mRNA (8-fold to 26-fold), protein (20-fold to 39-fold) and procoagulant activity (5-fold to 13-fold) in endothelial cells in a time-dependent manner. The time-course of heme-mediated TF antigen expression paralleled the induction of procoagulant activity, with antibody blocking studies demonstrating specificity for TF protein. Interleukin (IL)-1α, and TNF-α are not involved in mediating the heme effect, as antibodies against these cytokines and IL-1-receptor antagonist failed to block heme-induced TF expression. Inhibition of heme-induced TF mRNA expression by sulfasalazine and curcumin suggested that the transcription factor nuclear factor kappaB is involved in mediating heme-induced TF expression in endothelial cells. Conclusions: Our results demonstrate that heme induces TF expression by directly activating endothelial cells, and that heme-induced endothelial TF expression may provide a pathophysiologic link between the intravascular hemolytic milieu and the hemostatic perturbations previously noted in patients with hemolytic anemia including sickle cell disease.

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